JP2006340099A - Gateway unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gateway unit capable of suppressing communication quantity and smoothly relaying with sufficient reliability of data communication. <P>SOLUTION: The gateway unit in which a plurality of networks connected to a plurality of control units by communication lines are formed, which performs receiving processing and transmitting processing of a communication frame by is characterized in that it comprises: a receiving means for receiving the communication frame from the network and storing in a communication frame buffer; a relay priority setting means for setting a relay priority to the communication frame stored in the frame storage buffer; and a transmitting means for transmitting the communication frame stored in the frame storage buffer to the network based on the relay priority. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a gateway apparatus in which a plurality of networks in which a plurality of control units are connected by communication lines are formed, and the plurality of networks are connected to perform communication frame reception processing and transmission processing.

  For example, as a large number of control units that electronically control on-board equipment are adopted in a vehicle, there is an increasing demand for sharing data among the control units and performing distributed control and cooperative control in each control unit. For example, in a vehicle, each control unit is networked according to the classification of body systems such as seats and doors, power train systems such as engines and electronic throttles, and multimedia systems such as navigation devices, VICS, and ETC. Are being considered to be connected via a gateway device capable of relaying communication frames as data.

  As the gateway device, a monitoring control support device that operates stably even when a device subject to monitoring control, a terminal or a communication line used for the monitoring control falls into a congestion state, or a failure occurs in them. Has been devised (see Patent Document 1).

  In addition, in order to make the data communication sufficiently reliable and enable relaying smoothly, the data body includes incidental information of the data body, and the incidental information includes information on the type of the data body and the multiplex communication line. In a data relay device that includes priority information set for each type of data body for collision arbitration, a buffer group consisting of buffers that temporarily hold data to be relayed for each data type, and a relay source multiplex communication line Priority adjustment means for adjusting the priority of the currently received data or received data based on the incidental information of the currently received data received this time and the incidental information of the received data already received and stored in the buffer. A data relay device provided has been devised (see Patent Document 2).

Japanese Unexamined Patent Publication No. 2000-307577 JP 2004-350055 A

  In the example of Patent Document 1, messages related to monitoring control sent from each device are collected, and accumulation in a queue and distribution from the queue are performed based on the messages. Sending increases the load on the communication line. Further, since it is necessary to store the message in the supervisory control support device, a corresponding storage area is required, which increases the cost of the device. In addition, there is a problem that a message relating to monitoring control is not transmitted, that is, a device having a different communication protocol cannot be monitored, and the flexibility of the system is lacking.

  In the example of Patent Document 2, it is necessary to set the priority of data on the side that transmits data to the relay device. Therefore, it is impossible to relay data from a device having no parameter for data priority, that is, a device having a different communication protocol.

  When the in-vehicle control unit is networked for each control system, communication networks with different purposes are mixed in the vehicle, and the gateway device needs to perform communication relay across the communication networks. When the communication protocol or communication speed differs depending on the communication network, the gateway device must absorb the difference in the communication protocol or communication speed of each communication network, so the complexity of the gateway device and the increase in processing load are inevitable. Further, simply relaying received data as it is increases the amount of communication and unnecessarily increases the load on the receiving control unit.

  For example, when the gateway ECU, which is a gateway device, relays between a control communication network having a relatively high communication speed of 1 Mbit / sec and a body communication network having a relatively low communication speed of 10 kbit / sec, If data from the control communication network is relayed to the body communication network, the communication capacity of the body communication network will be exceeded, so the priority of communication frames relayed to the body communication network will be lowered, or communication frame relay processing will be performed. Measures are taken such as limiting the timing and suppressing the frequency of relaying to the body communication network.

  However, when the communication speed of the body communication network is 1 Mbit / sec, the communication capacity of the body communication network does not exceed, but excessive data is sent to the control unit (ECU) included in the body communication network. This increases the communication processing load. Also, the relay processing load of the gateway device increases.

  Some communication protocols can include communication priority in a communication frame. However, the communication protocol cannot always be used due to the configuration of the gateway device and the network.

  Against the background of the above problems, an object of the present invention is to provide a gateway apparatus that can sufficiently perform relaying with sufficient reliability of data communication while suppressing the amount of communication.

Means for Solving the Problems and Effects of the Invention

  The present invention provides a gateway device for solving the above problems. That is, according to claim 1, in the gateway device in which a plurality of networks in which a plurality of control units are connected by communication lines are formed and the plurality of networks are connected to perform communication frame reception processing and transmission processing, Receiving means for receiving and storing the communication frame in the frame buffer, relay priority setting means for setting the relay priority for the communication frame stored in the frame buffer, and relay priority for the communication frame stored in the frame buffer And a transmission means for transmitting to the network based on the above.

  According to the present invention, it is possible to set the relay priority even if the communication frame sent from the control unit does not include relay priority information or incidental information. Furthermore, since it does not depend on the communication protocol of the network, there is an advantage that it can be flexibly handled.

  According to the second aspect, the relay priority setting means in the gateway device of the present invention stores the received communication frame in the frame buffer when the communication frame is already stored in the frame buffer. The relay priority can be made higher.

  The fact that the communication frame is already stored in the frame buffer means that the communication frame is waiting to be transmitted. If a communication frame is received even though a previously received communication frame has not yet been transmitted, it can be determined that the communication frame should be transmitted immediately. With the above configuration, the relay priority can be set appropriately according to the communication state of the network, and the efficiency of relaying the communication frame can be improved.

According to claim 3, the relay priority setting means in the gateway device of the present invention can be configured to set the relay priority based on the content of the received communication frame.

  In the above configuration, it is not necessary to include relay priority information or incidental information in the content of the received communication frame, so that it is possible to set the relay priority without depending on the network communication protocol.

  According to claim 4, the communication frame in the gateway device of the present invention includes communication type information indicating the type of communication content, and the relay priority setting means sets the relay priority according to the communication type information. Can do.

  The transmission timing of the communication frame varies depending on the network. If the communication frame contains communication type information indicating the type of communication content such as from which network, what type of data, etc., for example, relay of the communication frame from a network that periodically transmits in a short cycle The priority is set lower and the relay priority of the communication frame from the network that transmits only when an event such as a switch state change occurs is higher, so that necessary data is relayed at an appropriate timing. be able to.

  According to the fifth aspect, the communication frame in the gateway device of the present invention can include the identification information of the control unit, and the relay priority setting means can set the relay priority according to the identification information.

  Even if included in the same network, the transmission timing of the communication frame may differ depending on the control unit. There is also a control unit that is connected to a network and transmits a communication frame only in a specific mode such as a failure diagnosis mode or a maintenance mode. With the above configuration, the priority of the communication frame from the specific control unit can be set to an appropriate value, and the efficiency of relaying the communication frame can be improved.

  According to the sixth aspect of the present invention, the gateway device of the present invention can include a monitoring unit that monitors the communication state of the network, and the relay priority setting unit can set the relay priority based on the communication state.

  Even with the above configuration, the relay priority of a communication frame from a network that periodically transmits in a short cycle is set lower, and the communication frame is relayed from a network that transmits only when an event such as a switch state change occurs. By making the priority higher, necessary data can be relayed at an appropriate timing.

  According to claim 7, the monitoring means in the gateway device of the present invention monitors the reception amount of the communication frame, and the relay priority setting means sets the relay priority according to the reception amount of the communication frame. Can do.

  When a communication frame exceeding the normal reception amount is received due to a failure of the control unit, etc., by setting the relay priority of the communication frame lower, it is made difficult to be included in the predetermined range by the search means It is possible to suppress transmission of unnecessary communication frames.

  According to the eighth aspect of the present invention, the gateway device of the present invention includes a search unit that searches for a relay frame having a relay priority within a predetermined range from communication frames stored in the frame buffer, and the transmission unit searches for the searched communication. A configuration can be adopted in which the frame is transmitted to the network.

  The required frequency or content of the communication frame differs depending on the network or the control unit. With the above configuration, a necessary communication frame can be sent to a network or a control unit when necessary, and the efficiency of relaying the communication frame can be improved.

  According to the ninth aspect of the present invention, the gateway device of the present invention can take a configuration in which the predetermined range can be changed by a predetermined timing or a storage state of the communication frame in the frame buffer.

  FIG. 4 shows the relay priority Pri of each communication frame included in the frame buffer. FIG. 4A shows the relay priority of all frame buffers. For example, assuming that the predetermined timing is a 5 msec cycle and the transmission process of the communication frame is performed by the circulation process at that timing, the communication frame having the highest relay priority Pri shown in FIG. Only search and send. In the next round processing, a communication frame having a relay priority Pri higher than 2 shown in FIG. In the next rounding process, a communication frame having a relay priority Pri higher than 3 shown in FIG. With the above configuration, it is possible to transmit a necessary communication frame at an appropriate timing, and it is possible to improve the efficiency of relaying the communication frame.

  Further, for example, when only the communication frame with the highest relay priority Pri is searched and transmitted, and the number of communication frames with the relay priority Pri is less than a predetermined value, the communication with the relay priority Pri of 2 is performed. A frame may be searched and transmitted by a number less than the predetermined value. Also with this configuration, it is possible to improve the efficiency of relaying communication frames.

  The purpose of providing a gateway device that can relay data quickly even in situations where there is a large amount of relay data is to set a relay priority for each received communication frame, and the relay priority is included in a predetermined range This is realized by a configuration that searches for and transmits communication frames.

  Hereinafter, embodiments of the present invention will be described based on an example in which the gateway device of the present invention is applied to a vehicle. The scope of application of the gateway device of the present invention is not limited to a vehicle, and can be applied to, for example, a network communication device.

  FIG. 1 is a block diagram showing the overall configuration of the gateway device and peripheral network of the present invention. Various control units that electronically control on-vehicle equipment form a network, and are connected to each other via a communication bus and further a gateway device.

  In the example of FIG. 1, a body system network is configured on the communication bus 1, and an ECU-A that controls the door lock and an ECU-B that adjusts the position of the seat are connected. In addition, a powertrain network is configured on the communication bus-2, and an ECU-C that controls the engine, an ECU-D that controls the transmission, and an ECU-E that controls the brake are connected.

  As shown in FIG. 2, the gateway device 10 includes a first communication I / F 16 and a second communication I / F 17 that are reception means and transmission means of the present invention to which the communication bus-1 and the communication bus-2 are connected, MPU11 which controls the data transmission between the communication bus-1 and the communication bus-2, and the MPU11 performs various processes performed by the gateway device 10. The MPU 11 that is the relay priority setting means, threshold setting means, search means, and monitoring means of the present invention stores a RAM 12, a flash memory 13 and the like that store data or programs used when executing various processes including a data transmission process. A ROM 14 is connected.

  The ROM 14 stores, for example, a main program 14p for executing various processes performed by the gateway device 10 and device identification information 14b such as a device number of the gateway device 10. The flash memory 13 stores, for example, a processing program 13p for executing various processes performed by the gateway device 10. The MPU 11 executes the main program 14p stored in the ROM 14, and reads and executes a necessary processing program 13p from the flash memory 13. The processing program 13p can be updated by the MPU 11. The update process is performed by an input operation unit such as a switch (not shown) provided on the instrument panel, for example.

  Data necessary for executing various processes is read from the RAM 12, the flash memory 13, and the ROM 14 by the MPU 11. The processing result is stored in the RAM 12 or the flash memory 13 by the MPU 11. For example, an address table including addresses of ECU-A to ECU-E is stored in the RAM 12, and a filtering policy such as a transmission source and / or a transmission destination that blocks data transfer is stored in the flash memory 13. The MPU 11 performs communication frame relay processing with reference to the address table and the filtering policy. It is also possible to use only the flash memory 13 without using the RAM 12.

  The communication protocols used in the communication bus-1 and the communication bus-2 are known token passing systems, CSMA / CD (Carrier Sense Multiple Access with Collision Detection) systems, and TDMA (Time Division Multiple Access: Various known protocols such as a time division multiple access method may be employed. It is also possible to employ different communication protocols for each network. The first communication I / F 16 and the second communication I / F 17 have a circuit configuration including known communication LSIs 16a and 17a corresponding to the communication protocols of the respective networks.

Reception of a communication frame from the communication bus-1 or communication bus-2 is performed using at least one of the following (1) or (2).
(1) The communication frames received from the communication bus-1 or the communication bus-2 are stored in the buffers 16b and 17b that are included in the communication I / F 16 and the second communication I / F 17 and configured by a RAM or the like. The received communication frame is stored in each buffer by a method of directly transferring the communication frame from the communication LSIs 16a and 17a to each buffer, or by a control program operated by a CPU (not shown) that performs overall control of the communication I / Fs 16 and 17. Any method of transferring communication frames from the LSIs 16a and 17a to the buffers 16b and 17b may be used.
(2) The communication frame received from the communication bus-1 or the communication bus-2 is fetched from the communication I / F 16 or the second communication I / F 17 by the communication driver program included in the main program 14p, and an area is secured in the RAM 12. Stored in the buffer 12a.
When a communication frame is received from communication bus-1 or communication bus-2, a communication frame reception flag indicating that the communication frame has been received is set. An area for the communication frame reception flag is secured for each communication frame.

  The number of communication buses to be connected is not limited, and a safety network such as a multimedia system and an air bag may be included in the configuration in addition to a power train system and a body system network. In this case, a communication I / F corresponding to the communication protocol of the added network is also added.

  As shown in FIG. 10, the communication frame includes a header portion and a data portion, and a data body is written in the data portion. The header portion includes communication type information representing network types such as powertrain and body systems, device identification information of ECU-A to ECU-E, and the meaning of communication frames such as vehicle speed and engine speed. ID to be transmitted and the transmission destination of the communication frame. Further, a data length code (DLC) indicating the length of the data body may be included.

FIG. 3 shows a configuration example of a frame buffer in which an area is secured in the RAM 12. Any of the following (1) to (3) may be used for the configuration of the frame buffer.
(1) An area is secured for each communication frame ID included in the data portion. That is, the contents of the data part with the communication frame ID 0 are stored in DATA0, and the contents of the data part with the communication frame ID m are stored in DATAm. In this case, one relay priority area is secured for each ID.
(2) The received communication frame is divided into bytes, for example, and stored in the data area. For example, if the data portion of the communication frame is 8 bytes, m in the data area in FIG. 3 is 8, and 1 byte is stored in 1 to 8 in the data area. In this case, the relay priority area may be one. That is, the frame buffer has an area for each ID.
(3) The received communication frame is converted into the format of the destination communication frame and stored in the data area. It may be stored in batches for each ID of the communication frame to be transmitted as in (1), or may be stored in units of 1 byte as in (2). In this case, one relay priority area is secured for each transmission destination.

  With the configuration as described above, the gateway device 10 stores the communication frame received from the communication bus-1 through the first communication I / F 16 in the frame buffer and transmits it to the communication bus-2 via the second communication I / F17. That is, it relays. For example, the communication frame from ECU-A is relayed to ECU-C to ECU-E. Moreover, you may relay the communication frame from ECU-A to ECU-B connected to the same communication bus-1. Conversely, the communication frame from ECU-E connected to communication bus-2 is relayed to ECU-A and ECU-B connected to communication bus-1. Similarly, the communication frame from ECU-E may be relayed to, for example, ECU-C connected to the same communication bus-1.

(Relay priority setting)
When a communication frame received using FIGS. 5 and 8 is stored in the frame buffer, a relay priority setting process for increasing the relay priority of the communication frame when the communication frame is already stored in the frame buffer. Will be described. FIG. 5 is a diagram showing the transition of the relay priority of the communication frame. FIG. 8 is a flowchart of the relay priority setting process stored in the ROM 14 of the gateway device 10 and included in the main program 14p executed by the MPU 11. This process is repeatedly executed together with other processes included in the main program 14p.

  When the communication frame is received, that is, when the communication frame reception flag is set and the communication frame is stored in the communication frame buffer 16b, 17b or the buffer 12a (S1: Yes), it corresponds to the ID included in the received communication frame. Referring to the frame buffer to be checked, it is confirmed whether a communication frame has already been stored. If no communication frame is stored (S2: No), the relay priority is increased by one step (S4), the received communication frame is stored in the frame buffer, and the corresponding communication frame reception flag is cleared (S5). ). At this time, the contents of the buffers 16b and 17b or the buffer 12a may be cleared to zero. This corresponds to the case where the new communication frame shown in FIG. 5A is received, and the relay priority Pri is set to a minimum of 3.

  On the other hand, when the communication frame is already stored (S2: Yes), it is checked whether the relay priority of the communication frame is the highest. If the relay priority is not the highest (S3: No), the relay priority is set. Increase by one step (S4). Then, the received communication frame is stored in the frame buffer (S5). At this time, the contents of the buffers 16b and 17b or the buffer 12a may be cleared to zero. This corresponds to FIG. 5B in which the communication frame is received after receiving the new communication frame in FIG. 5A, and the relay priority Pri is increased by one step from the lowest 3 to 2.

  Note that the processing from step S2 to step S5 described above is performed until all the communication frames stored in the buffers 16b, 17b or the buffer 12a are extracted (S6: No).

(Another example of relay priority setting 1)
In the relay priority setting process of FIG. 8, when the communication type information is included in the received communication frame ID, a method of setting the relay priority according to the communication type information may be used. For example, for a communication frame periodically sent in a short cycle, when the relay priority Pri of the frame buffer corresponding to the communication type information is set to a minimum of 3 and an event such as a switch state change occurs For communication frames sent only to, the relay priority of the frame buffer corresponding to the ID is set to the highest one.

  The frame buffer relay priority set corresponding to the communication type information is stored in advance in the flash memory 13 or the like. Further, a method of setting the relay priority for each communication type information according to the communication frequency described later may be used together.

(Another example 2 of relay priority setting)
In the relay priority setting process of FIG. 8, when the device identification information is included in the received communication frame ID, a method of setting the relay priority according to the device identification information may be used. For example, as shown in FIG. 7, when a failure diagnosis device 20 for performing failure diagnosis is connected and a communication frame is received from the failure diagnosis device 20, it is determined that the entire vehicle is operating in the failure diagnosis mode. The relay priority of the frame buffer that stores the communication frame from the fault diagnosis device 20 is set to the highest 1, and the communication frame that is sent only when an event such as a switch state change occurs The relay priority of the frame buffer corresponding to the device identification information is set to 2, and the relay priority of the frame buffer corresponding to the ID is set to a minimum of 3 for communication frames that are sent periodically.

  The frame buffer relay priority set corresponding to the device identification information is stored in advance in the flash memory 13 or the like. Also, a method of setting the relay priority according to the communication frequency described later may be used together.

(Another example 3 of relay priority setting)
In the relay priority setting process of FIG. 8, when communication type information or device identification information is included in the received communication frame ID, a method of setting the relay priority according to the reception frequency of the communication frame may be used. For example, as shown in FIG. 6, when a communication frame from ECU-B periodically sent at a predetermined cycle is sent at a half cycle of the predetermined cycle for some reason, the relay priority is higher than usual. It will be set. Then, although a communication frame is sent to ECU-C twice as often as usual, the load of reception processing in ECU-C may increase and affect the operation of ECU-C itself.

  Therefore, the communication frame transmission cycle for each communication type information or device identification information is stored in the flash memory 13 or the like as a reference cycle, and a communication frame for each communication type information or device identification information is used by using the timer function of the MPU 11. When the reception period is measured, for example, when the communication frame reception period from the ECU-C is half of the normal, the frame buffer corresponding to the communication frame from the ECU-C is one rank lower than the relay priority normally set. Set to relay priority.

  Store the ratio between the actual frame reception period and the reference period and the reduction range of the relay priority rank as map data in the flash memory 13 or the like, and calculate the ratio between the frame reception period and the reference period in the frame reception process, Select the relay priority rank reduction width corresponding to the ratio calculated with reference to the map data, and reflect the reduction width selected in advance for each ID relay priority stored in the flash memory 13 or the like. You may make it do.

(Communication frame transmission)
A communication frame transmission process for transmitting a communication frame stored in the frame buffer will be described with reference to FIG. This process is stored in the ROM 14 of the gateway device 10, is included in the main program 14p executed by the MPU 11, and is repeatedly executed together with other processes included in the main program 14p.

  First, it is checked whether or not a communication frame is stored in the frame buffer indicated by the pointer content. If a communication frame is stored (S11: Yes), it is checked whether the relay priority corresponding to the communication frame is equal to or higher than a set threshold value. When the relay priority is equal to or higher than the set threshold (S12: Yes), the communication frame is transmitted (S13). Then, the contents of the frame buffer including the relay priority are cleared (S14, state shown in FIG. 5C).

  Next, the contents of the pointer are incremented to the position of the next frame buffer (S15), and the processes from step S11 to S15 are repeated until the transmission process end condition is satisfied. On the other hand, when the communication frame is not stored in the frame buffer indicated by the content of the pointer (S16: YES) (S11: No), the content of the pointer is incremented to check whether there is a communication frame in the next frame buffer (S15). → S11).

  The pointer indicates the position, that is, the address of the frame buffer waiting for transmission among the data body indicated by the ID stored in the frame buffer or individual data. The initial value of the pointer is the top address of the frame buffer, and when incremented when the pointer content is the end address of the frame buffer, the pointer returns to the top address of the frame buffer.

Any of the following may be used as the transmission processing end condition.
(1) The transmission processing end condition is satisfied after a predetermined time has elapsed after the communication frame transmission processing is started. That is, the execution time of the communication frame transmission process is limited to a certain time.
(2) The transmission processing end condition is satisfied when a predetermined number of communication frames are transmitted.
(3) The transmission processing end condition is satisfied when a predetermined number of frame buffers are referred to. That is, the transmission process end condition is satisfied when the increment of the pointer reaches a predetermined value.

  Note that the maximum actual reception processing time should be predicted in advance based on physical constraints such as the communication speed of the communication bus and the minimum / maximum length of the communication frame, and time constraints such as the timing of repeated processing determined by the processing configuration of the gateway device. Can do. That is, the communication frame reception process and the main program 14p are configured so that all communication frames stored in the buffers 16b and 17b or the buffer 12a in one process can be stored in the frame buffer. Similarly, the communication frame transmission process and the main program 14p are configured so that at least one communication frame can be transmitted by the circulation process.

  Although the embodiments of the present invention have been described above, these are merely examples, and the present invention is not limited to these embodiments, and the knowledge of those skilled in the art can be used without departing from the spirit of the claims. Various modifications based on this are possible.

The block diagram which shows the structure of a gateway apparatus and a periphery network. The block diagram which shows the structure of a gateway apparatus. The figure which shows an example of a structure of a frame buffer. The figure explaining the method of searching a thing higher than a predetermined relay priority. The figure which shows the change of the relay priority in a communication frame reception process and a communication frame transmission process. The figure used for description of the process which changes a relay priority by the change of the receiving period of a communication frame. The figure used for description of the process which changes a relay priority by ID (apparatus identification information). The flowchart explaining a communication frame reception process. The flowchart explaining a communication frame transmission process. The figure which shows an example of a structure of a communication frame.

Explanation of symbols

10 gateway device 11 MPU (relay priority setting means, threshold setting means, search means, monitoring means)
12 RAM
14 ROM
16 First communication I / F (reception means, transmission means)
17 Second communication I / F (reception means, transmission means)

Claims (9)

In a gateway apparatus in which a plurality of networks in which a plurality of control units are connected by communication lines are formed, and the plurality of networks are connected to perform communication frame reception processing and transmission processing.
Receiving means for receiving a communication frame from the network and storing it in a frame buffer;
Relay priority setting means for setting a relay priority for a communication frame stored in the frame buffer;
Transmitting means for transmitting the communication frame stored in the frame buffer to the network based on the relay priority;
A gateway device comprising:   The relay priority setting means, when storing the received communication frame in the frame buffer, further increases the relay priority of the communication frame when the communication frame is already stored in the frame buffer. The gateway device according to 1.   The gateway apparatus according to claim 1, wherein the relay priority setting unit sets the relay priority based on the content of the received communication frame. The communication frame includes communication type information indicating the type of communication content,
The gateway device according to claim 1, wherein the relay priority setting unit sets the relay priority according to the communication type information. The communication frame includes identification information of the control unit;
The gateway device according to claim 1, wherein the relay priority setting unit sets the relay priority according to the identification information. Comprising monitoring means for monitoring the communication state of the network;
The gateway apparatus according to claim 1, wherein the relay priority setting unit sets the relay priority based on the communication state. The monitoring means monitors the received amount of the communication frame;
The gateway apparatus according to claim 6, wherein the relay priority setting unit sets the relay priority according to a reception amount of the communication frame. Search means for searching for a relay frame in which the relay priority is included within a predetermined range from communication frames stored in the frame buffer;
The gateway device according to claim 1, wherein the transmission unit transmits the searched communication frame to the network. The gateway device according to claim 8, wherein the predetermined range can be changed by a predetermined timing or a storage state of the communication frame in the frame buffer.

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